Automated robotic systems can build cars – or decommission nuclear sites. In hazardous environments, KUKA robots could be deployed to ensure human workers’ safety along the complete nuclear fuel cycle, from mining and enrichment to conversion. At a nuclear decommissioning facility in the UK, they currently support its decommissioning by sorting and size-reducing waste as well as swabbing and housekeeping. A second system to be installed subsequently will replace the lids on waste boxes and bolt them.

The initial situation

A nuclear facility is currently undertaking a huge clean-up operation which includes decontamination and decommissioning. As part of the clean-up of a key legacy facility on the site, a new plant is due to be commissioned in 2018. When complete, the plant will treat nuclear waste recovered from the storage silo programme, immobilise it and prepare it for long term storage. With the dangers involved for workers from exposure to harmful radiation, the contaminated nuclear waste is handled by robots, either automated or remotely by an operator. In order to evaluate their suitability for the new plant, a test rig with KUKA robots was set up. The goal was to determine whether they would be able to pick up, move and place simulated nuclear waste in a test environment.

The task

Once the plant begins operating, the robots need to be able to safely process nuclear waste recovered from ponds and silos across the plant, preparing it for long-term storage. This includes drums, cans and containers as well as plant equipment, graphite blocks, sludge carryover or specific waste types such as Zeolite skips, wet way baskets etc.

The robots will be used to empty the contents of skips which have been stored for a number of years on-site. The waste is picked out of one skip and placed on a sorting table. Depending on the item it can be drilled to release trapped liquids, or cut up to make smaller and easier to repack. The waste is all then repacked in to a new skip ready to be sent to a new storage facility.

The challenge is speed and efficiency combined with being able to perform the operations remotely to prevent the staff being exposed to the radiation. KUKA Systems UK Ltd – unlike other robot manufacturers – developed the manual controls to enable on operator to perform specific non-automated tasks (e.g. picking up waste from the table). Via a joystick, the robots are operated remotely to handle the waste, including heavy and bulky items (up to 350 kg in weight) and to perform disruption tasks as well as general house-keeping duties. Having proved their mettle in the automotive industry through many years, the robots represent a reliable, efficient solution for this particular application.

The solution

The robots are already available on the market and are most commonly used in foundries and on car production lines. The developed solution utilises a linear layout of processing equipment with a number of heavy duty standard industrial robots positioned around a Waste Handling Table. Tests began in 2014 with a system based on three KUKA KR 500 robots. The nuclear decommissioning facility picked them because they could handle high payloads (up to 500 kg) while weighing less than three tonnes and because of their ability to operate in tele operation mode and programme mode. And there were other important facts: the robot technology is well proven, there is a range of tools and service provisions available and the robots work with high accuracy and a repeatability of 0.08 mm.

Robot control is easily automated and integrated using unique KUKA
joysticks

The main size reduction tool, a hydraulic shear, will be used for most of the variety of different types of waste items in the future. However, KUKA additionally designed and built a number of tools, based on commercial off the shelf equipment that was adapted to be used on the robots. These included hydraulic grabs and general purpose gripper jaws as well as tools for drilling, bolt removal, pumping, spraying and others used for general waste recovery and handling. KUKA also provided a joystick unit that is unique in this market and not available from other suppliers. It allows an operator to control the KUKA robot manually. The trials found that the robots have high degree of dexterity and control, both in manual tele operation mode and in auto mode. Programmed sequences significantly reduced the operator’s workload.

Tests showed that the robots met necessary operational functionality, making them suitable for their future work environment. Following the successful tests of the rig, the customer decided to have a second KUKA solution installed once the plant commences operation in 2018. The automated robotic solution will be used to re-lid the skips and bolt the lids on them.

KUKA solutions with their well proven, high reliability are perfectly suited to facilitate a safer, quicker and cheaper decommissioning. Combined with outstanding technical support at the premises offered by a KUKA staff member, the automated robotic system offers the high quality results necessary for our nuclear applications.